Over the past couple of years, NASA has been watching flashes of light on the moon. It’s not a new phenomenon; they began observing the moon’s surface to prepare for the future lunar mission project. The explosions are caused by meteoroids hitting the moon. Bill Cooke, head of NASA's Meteoroid Environment Office at the Marshall Space Flight Center, says the flashes can be photographed with a backyard telescope.

That first detection—"I'll never forget it," he says--came on Nov. 7, 2005, when a piece of Comet Encke about the size of a baseball hit Mare Imbrium. The resulting explosion produced a 7th magnitude flash, too dim for the naked eye but an easy target for the team's 10-inch telescope.

A common question, says Cooke, is "how can something explode on the Moon? There's no oxygen up there."

These explosions don't require oxygen or combustion. Meteoroids hit the moon with tremendous kinetic energy, traveling 30,000 mph or faster. "At that speed, even a pebble can blast a crater several feet wide. The impact heats up rocks and soil on the lunar surface hot enough to glow like molten lava--hence the flash."

It doesn’t just happen during meteor showers. There are always pieces of natural space debris colliding with the moon. Link -via Geek Like Me